1. Field of the Invention
The present invention relates to a fixed focus imaging lens for forming an optical image of a subject on an image sensor, such as a CCD (Charge Coupled Device), CMOS (Complementary Metal Oxide Semiconductor), or the like, and an imaging apparatus provided with the imaging lens to perform imaging, such as a digital still camera, camera-equipped cell phone, personal digital assistance (PDA), smartphone, portable video game player, or the like.
2. Description of the Related Art
Recently, along with the spread of personal computers to homes and the like, digital still cameras capable of inputting image information obtained by imaging a landscape, a person, or the like to a personal computer have been spreading rapidly. In addition, more and more cell phones and smartphoes have built-in camera modules for inputting images. Such devices with imaging capabilities employ image sensors such as CCDs, CMOSs, and the like. Recently, these types of image sensors have been downsized greatly and, consequently, imaging devices as a whole and imaging lenses mounted on such devices have also been demanded to have more compact sizes. At the same time, the pixel count of image sensors has been increasing, thereby causing a growing demand for improvement of imaging lenses in resolution and performance. For example, performance corresponding to high pixel counts, such as more than 5 Mega Pixels, and more preferably more than 8 Mega Pixels is demanded.
For responding to such demands, it is conceivable to employ a relatively large number of lenses, such as a five- or six-lens configuration, in order to achieve, for example, reduction in overall length and improvement in resolution (refer to Korean Unexamined Patent Publication No. 2010-0040357 and Chinese Utility Model Publication No. 202067015 (U.S. Pat. No. 8,385,006)).